Recently, storage devices for storing information have notably come to be of mass capacitance, due to increases in amount of information handled in computers.
The main types of such storage devices are disc-type storage media such as hard discs and optical discs, and magnetic tapes.
Hard discs are superior to other two types in terms of the speed of recording and reproducing as well as the random accessibility, so that the hard discs are used as main storage devices. Disc-type storage media such as the optical discs as well as magnetic tapes are used for archives and backups.
Magnetic tapes are superior to disc-type recording media such as optical discs in terms of low price and recording capacity per portion volume, while the disc-type storage media such as the optical discs are superior to the magnetic tapes in terms of the random accessibility and saving property.
Therefore, there has been a great demand for a storage device which has the superior points of the magnetic tape and the disc-type storage medium such as the optical disc, which is a storage device of a low price, large capacity, and excellent random accessibility as well as saving property.
As a method for increasing the capacity of the disc-type storage medium such as the optical disc that is superior in terms of the random accessibility and the saving property, for example, there is a method proposed as shown in Patent Document 1 which stacks a plurality of recording media to be housed in a single case, develops the storage media extracted from the case, and loads them simultaneously to a plurality of recording/reproducing devices.
However, with such method, it is necessary to connect each recording medium with a special disc connector and allow connecting/separating actions between the storage media. Thus, the recording media need to be in a special structure, so that conventional production facilities cannot be utilized. This results in increasing the price. Further, each storage medium cannot be easily exchanged individually.
As the structure with which a plurality of recording media are stacked and housed in a single case, there are also proposed an optical disc cartridge disclosed in Patent Document 2, a continuous driving device disclosed in Patent Document 3, and a disc reproducing device disclosed in Patent Document 4. However, all of those are simply the devices which extract the recording medium one by one from a plurality of stacked recording media and set the medium to a recording/reproducing device, and those are not structured to load the plurality of recording media to a plurality of recording/reproducing devices simultaneously.
Among those, particularly the disc reproducing device of Patent Document 4 is disclosed in regards to a point which makes it easy to extract the recording medium that is a target to be drawn out through shifting the recording medium downwards when drawing out one of the stacked recording media to increase a gap between the recording medium and the recording medium positioned on the upper side thereof. However, this simply makes it easy to extract a single piece of recording medium, and the gap between the recording medium as the drawing target and the recording medium placed thereunder becomes decreased inversely from the above case. Thus, all the gaps between the recording media cannot be increased simultaneously. Therefore, it is not possible at all to achieve the object of developing the stacked recording media and loading those to a plurality of recording/reproducing device simultaneously.    Patent Document 1: Japanese Unexamined Patent Publication 2004-145994 (FIG. 1, FIG. 2)    Patent Document 2: Japanese Unexamined Patent Publication 2007-172726 (FIG. 1, FIG. 4, FIG. 5)    Patent Document 3: Japanese Unexamined Parent Publication Hei 8-31072 (FIG. 1, FIG. 2)    Patent Document 4: Japanese Unexamined Patent Publication Hei 10-283709 (FIG. 1, FIG. 6, Paragraph 0036)